A restaurant (hereinafter, including a pub or the like) generally accepts reservations in advance to secure customers. That is, a customer previously notifies the restaurant of reservation conditions relative to the use date, the number of persons, the contents of a dish and the like by the use of communication means such as the telephone or the Internet, and the result of the reservation is decided by whether the restaurant accepts the reservation. At that time, the restaurant sets a usage time limitation on the reservation, so that a plurality of reservations can be accepted without temporal overlap for a seat or a table (hereinafter, the “seat” is used in the case where a reservation unit is indicated). On the other hand, customers do not always come to the restaurant after making reservations, but they often come to the restaurant directly without reservations. In that case, when there is a vacant seat, the restaurant can guide the customer to the vacant seat, however, in the case of full house or even if there is a vacant seat, when the seat is a reserved seat, the restaurant declines entrance. Incidentally, the use time limitation is not usually imposed on the customers who directly come to the restaurant.
As stated above, for the restaurant or the like, the usage time of the customers who directly come to the restaurant is not necessarily clear, and it is often unclear when they go out of the restaurant, and therefore, there has been a problem that even if there is a customer who wishes to make a reservation thereafter, the restaurant can not accept the reservation. However, the customer presently taking the seat may go out of the restaurant soon. In the case where the customer actually goes out of the restaurant soon, a great loss of business chance occurs for the restaurant. Besides, for example, when there suddenly occurs such a state that a restaurant reservation must be made, although a restaurant having a vacant seat may be found immediately, there is also a case where a restaurant having a suitable vacant seat can not be found. If a restaurant outgo time (hereinafter simply called “outgo time”) when the customer presently taking the seat goes out the restaurant can be estimated, the restaurant can deal with sudden reservations, and business efficiency is improved, and a feeling of satisfaction of a customer who attempts to make a reservation is also improved.